Hi @ChenBr,
Welcome to the Auth0 Community!
The WebAuthn with FIDO Device Biometrics enrolls a device’s lock-screen unlock method. It’s up to the user to choose which unlocking method he chooses.
To distinguish between OSs you can use an Action where you check the event.request.user_agent’s value for example “Android” or “Mac OS X” and use this information accordingly.
If you have any other questions feel free to let us know.
Have a good one,
Vlad